
Don't get me wrong - if I'd left him for several hours, I'm sure he would have had accidents, but he was certainly in the routine of doing his business outside so it was very easy to carry that on.
He was boisterous yes, but I've had 5 Labradors now and they all have been boisterous! Training during the first couple of years makes all the difference and Melvin (my Exelby Lab) is so reliably steady now I can take him absolutely everywhere. I've not noticed any difference in terms of boisterousness between boys and girls, but I have found my boys are more 'needy' and less independent than my girls, but that is only based on my experience of 5 Labs - I'm sure a breeder would be able to help you more.
As for exercise, until the age of 12 months, they shouldn't really have very much (the rule of thumb is 5 mins per month of age, daily). As adults mine could walk all day, but are perfectly content with an hour or so.
Apart from hamsters, a Labrador was my first pet. It was a steep learning curve, and I think it would be with any breed of dog, but I can't imagine having anything else now and I do think they make great pets for anyone with the time to put in training and anyone who is able to ensure they're not left for too long.